To automatically tag new products as TryNow, you can leverage automatic tagging via Shopify Flow.
Follow these instructions to set up a Shopify Flow to tag your TryNow orders:
1. Navigate to the Apps section of Shopify and open the Shopify Flow app.
2. Click "Create workflow" and then "Select a trigger".
3. Select "Shopify" and then "Product Added to Store" under the list of triggers.
4. Select the "+" to add an Output and then click "Condition".
5. Click "Conditions", select "If all conditions are met" from the drop-down, then click "Add Criteria".
6. Select "Product" then select "tags"
7. Enter any tags you want to avoid making eligible for TryNow (ex; preorder, sale, etc.)
8. Click the "+" next to 'Otherwise' and click "Action". 
9. Select "Shopify" and then "Add product tags".
10. Enter "TryNow" in the Tags field.
11. Edit the name of your workflow.
12. Click "Turn on workflow".